Modulating lignin in plants

Abstract

Materials and methods for modulating (e.g., increasing or decreasing) lignin content in plants are disclosed. For example, nucleic acids encoding lignin-modulating polypeptides are disclosed as well as methods for using such nucleic acids to generate transgenic plants having a modulated lignin content.

1. A method of increasing lignin content in a plant, said method comprising: a) introducing into a plant cell an isolated nucleic acid comprising a regulatory region operably linked to a polynucleotide encoding a lignin-modulating polypeptide comprising an amino acid sequence having 95% or greater sequence identity to the amino acid sequence set forth in SEQ ID NO:149, said polypeptide having a nicotinamide adenine dinucleotide (NAD)-dependent epimerase/dehydratase domain; and b) selecting a plant produced from said plant cell that has at least a 35% increase in lignin content in a tissue of the plant as compared to the lignin content in tissue of a corresponding control plant that does not comprise said nucleic acid. 
     
     
       2. The method of  claim 1 , wherein said plant cell is capable of producing one or more lignin monomers. 
     
     
       3. The method of  claim 1 , wherein said plant is from a genus selected from the group consisting of  Agrostis, Avena, Festuca, Hordeum, Lolium, Medicago, Milium, Miscanthus, Panicum, Poa, Saccharum, Sorghum, Trifolium, Triticum , and  Zea.    
     
     
       4. The method of  claim 1 , wherein said plant is a species selected from the group consisting of: a  Miscanthus×giganteus  hybrid,  Miscanthus sinensis, Miscanthus sacchariflorus, Panicum virgatum, Populus balsamifera, Sorghum almum, Sorghum halepense, Sorghum vulgare , and  Saccharum  spp. 
     
     
       5. The method of  claim 1 , wherein said regulatory region is a promoter. 
     
     
       6. The method of  claim 5 , wherein said promoter is a lignin or cellulose biosynthesis promoter. 
     
     
       7. The method of  claim 6 , wherein said promoter is selected from the group consisting of SEQ ID NOs:345-354. 
     
     
       8. The method of  claim 5 , wherein said promoter is a tissue-preferential promoter. 
     
     
       9. The method of  claim 8 , wherein said tissue is secondary cell wall, vascular, stem, pith, xylem, phloem, root, tuber, or leaf tissue. 
     
     
       10. The method of  claim 5 , wherein said promoter is a cell type-preferential promoter. 
     
     
       11. The method of  claim 10 , wherein said cell is a sieve, laticifer, companion, sclerenchyma, or xylem cell. 
     
     
       12. The method of  claim 5 , wherein said promoter is an inducible promoter. 
     
     
       13. The method of  claim 1 , wherein said plant is from a genus selected from the group consisting of  Eucalyptus, Oryza, Pinus, Populus, Prunus , and  Quercus.    
     
     
       14. The method of  claim 1 , wherein said method further comprises introducing into said plant cell a nucleic acid encoding a second lignin-modulating polypeptide operably linked to a second regulatory region. 
     
     
       15. The method of  claim 14 , wherein said nucleic acid encoding a second lignin-modulating polypeptide operably linked to a second regulatory region is present on a second recombinant nucleic acid construct. 
     
     
       16. A plant produced by the method of  claim 1 . 
     
     
       17. Progeny of the plant of  claim 16 , wherein said progeny comprises the polynucleotide encoding the lignin-modulating polypeptide comprising an amino acid sequence having 95% or greater identity to the amino acid sequence set forth in SEQ ID NO: 149, said polypeptide having a NAD-dependent epimerase/dehydratase domain, and wherein tissue of said progeny has at least a 35% increase in lignin content as compared to the lignin content in tissue of a corresponding control plant that does not comprise said nucleic acid. 
     
     
       18. The progeny of  claim 17 , wherein said progeny is from a genus selected from the group consisting of  Agrostis, Avena, Festuca, Hordeum, Lolium, Medicago, Milium, Miscanthus, Panicum, Poa, Saccharum, Sorghum, Trifolium, Triticum , and  Zea.    
     
     
       19. The progeny of  claim 18 , wherein said progeny is a species selected from the group consisting of: a  Miscanthus×giganteus  hybrid,  Miscanthus sinensis, Miscanthus sacchariflorus, Panicum virgatum, Populus balsamifera, Sorghum almum, Sorghum halepense, Sorghum vulgare , and  Saccharum  spp.